1. Field of the Invention
The present invention relates to framing structures for the support of conduit, fixtures, piping and other equipment and accessories used in process piping, plumbing, heating, cooling and electrical systems of buildings and other industrial and commercial applications and particularly, to an improvement in strut which is the primary component of structures that support such systems.
2. Description of the Prior Art
"Strut" is a structural member defined in metal framing construction industry as continuous slot channel with inturned lips. Strut has been widely used since World War II as a framing member in buildings for supporting fixtures and equipment, piping, conduit, etc. needed for the operational systems of commercial buildings, refineries, power plants, and other industrial and commercial applications. The strut support system may be either attached to the building structure or independent of it, thus making it useful also in a number of industrial applications where freestanding support structures are needed. Metal strut, which can be cold rolled from steel or extruded from aluminum into a variety of sizes and lengths, is a stronger framing member than wood and more versatile than welded construction because it requires only hand tools for assembly and, unlike welded structures or framing, can be disassembled.
Strut can be used effectively in both vertical and horizontal orientations and numerous accessories and fittings are available for connecting framing members or anchoring equipment to the strut. One such typical fitting, a spring nut, is shown in FIG. 1 of the accompanying drawings. The spring nut is usually rectangular in shape with two opposing beveled corners and parallel grooves along the narrower edges, so that it may be inserted anywhere along the slot of the strut and then turned 90.degree. to clamp onto the inside edges of the strut. A spring is attached to the underside of the nut to hold it in position while bolts are inserted into the nut to anchor various fittings, connectors, brackets, etc., to the strut. Although time-consuming, this procedure is relatively simple when the first connectors and fittings are attached to the strut. However, as more joints and fittings are mounted to the slot of the strut, the strut becomes more congested and correspondingly, it becomes more difficult and even more time-consuming to add or remove a nut or other fitting.
The present invention is an improved form of strut which overcomes this drawback in the prior art and maximizes the usefulness and versatility of strut. The present invention is designed to allow attachments to be mounted to the strut without the use of nuts, thereby saving time in assembling and repositioning attachments. The elimination of the need for nuts and spring nuts also provides savings by reducing the parts and materials needed in inventory during construction projects. This invention makes it possible to attach fittings more easily in crowded areas of the structure, thus maximizing the potential number of attachments which can be made. The strut of this invention is designed so that it can be cold rolled by a continuous process, or extruded, in a manner similar to that used to make prior art strut. Since the present invention has the same outer configuration as the strut of the prior art and can be used with all the same accessories and attachments, it may be utilized interchangeably with current systems and standard fittings. Thus, the new form of strut of this invention, which eliminates the need for nuts, has all the advantages and uses of conventional strut and is compatible with existing strut and accessories, while providing additional advantages of increased versatility and reduced construction costs and inventory requirements.